Various systems have been conventionally developed with respect to an apparatus for drying sludge and food wastes, and a carrier system to be equipped in the apparatus. As such systems having relevancy with the present invention, there can be found “a drier apparatus” disclosed in the patent document 1, and “screw conveyer” disclosed in the patent document 2.
The drier apparatus disclosed in the patent document 1 includes a cylindrical chamber in which a pair of screw conveyers each including a tubular shaft, and carrier blades arranged on an outer surface of the tubular shaft is housed, a motor for rotating the screw conveyers, and rotary joints rotatably supporting the tubular shaft at its opposite ends in order to allow steam, that is, heat medium having been heated in advance, to flow in the tubular shaft. The drier apparatus disclosed in the patent document 1 has advantages that no exhaust gas and soot are generated while the drier apparatus is in operation, and that the drier apparatus can be readily handled and maintained.
The screw conveyer disclosed in the patent document 2 includes rotary carriers arranged in parallel with each other, each rotary carriers including two tubular shafts arranged in a common imaginary plane such that the tubular shafts are rotatable by a motor, and a plurality of semicircular carrier blades fixed on an outer surface of the tubular shafts such that the carrier blades form a part of an imaginary spiral plane about an axis of each of the tubular shafts. A drier apparatus equipped with the screw conveyer disclosed in the patent document 2 has an advantage that a material to be carried (a material to be dried) is difficult to be adhered to the tubular shafts, and to be clogged in the tubular shafts.